A. Field of the Invention
This invention relates to carpet comprising a primary backing and a pile consisting of fibers attached to the primary backing. More specifically, the invention relates to carpet that resists soiling and is substantially impervious to water. By "substantially impervious to water" is meant that when one gallon (3785 ml) of water is poured onto the facing of the carpet from a height of less than 3 centimeters and allowed to stand for sixty (60) hours, less than 300 ml or (8%) of the water passes through the primary backing of carpet.
The term fiber as used herein includes fibers of extreme or indefinite length (i.e., filaments) and fibers of short length (i.e., staple). The term yarn as used herein means a continuous strand of fibers.
B. Description of the Prior Art
The typical carpet for residential applications is a wall-to-wall carpet which has a primary backing material, such as polypropylene or jute, stitched with closely spaced erect loops or cut loops of polyamide yarn which extend upwardly from the backing to form a tufted structure (i.e., pile). The underside of the primary backing is coated with an adhesive composition. The adhesive anchors the tufts in the primary backing and is applied to the backing in the form of a latex compounded emulsion which is then dried with heat to cure the adhesive. In most instances, a secondary backing is applied to the underside of the primary backing before the adhesive is dried and cured. The typical carpet is normally installed with an underpad being placed between the carpet and floor. The underpad enhances the cushioning effect and wear-life of the carpet. The carpet and underpad are referred to herein as the carpet system. Usually, the polyamide yarn is coated with a fluorochemical, either before or after the carpet is made, to enhance the soil resistant and soil repellant properties of the carpet.
The typical carpet system is vulnerable to water. Water which spills or otherwise comes into contact with the exposed surface (i.e. facing) of the carpet quickly wets the pile, passes through the primary backing, adhesive composition, secondary backing, and is absorbed by the underpad which serves as a reservoir for the water. Drying of the carpet system, on the other hand, is a slow process in which moisture slowly migrates upwardly from the underpad back through the components of the carpet system to the facing where it then evaporates into the surrounding atmosphere. (The drying time can be lessened somewhat by use of air driers, towels, sponges, vacuums, etc. to remove moisture from the facing.) In the meantime, however, the presence of moisture in the carpet system components causes mildew and rotting of the components as well as any wooden floors in contact with the underpad. In the case of urine, there is the additional problem, namely, that of a prolonged and offensive odor. In the case of an artificially-colored soft drink which stains the carpet, the staining of the carpet persists until the drying process is completed, for example, while the soft drink can be immediately sponged from the carpet facing, drink when stored in the underpad will slowly but continually work its way upward from the underpad and restain the facing.
The vulnerability of the typical carpet system to water and water based substances gives rise to a very real dilemma, namely, that of washing the carpet. Normally, if a sufficient amount of water is used to effectively wash stains, soil and odors from the carpet, a portion of the water passes through the carpet and is absorbed by the underpad which is undesirable for reasons given above. On the other hand, if water is sparingly used so as to prevent it from getting down into the underpad, effective cleaning of the carpet often is not possible. Therefore, even though carpet fibers are treated with fluorochemicals for the purpose of making the typical carpet system more resistant to soiling and staining, as a practical matter, once the carpet has been stained or soiled, there is no easy way to effectively remove the stain or soil from the carpet without wetting the underpad and creating yet another and, perhaps, even a more serious problem.